Vehicle air conditioning systems can provide a driver with a comfortable environment during warm and/or humid ambient driving conditions. Air from the vehicle cabin is passed over an evaporator that cools the air and condenses water vapor from the air, thereby conditioning the cabin air to improve driver comfort. Air conditioning systems may be sized with a high cooling capacity so that the driver may be comfortable during particularly warm days. However, it may not be desirable to operate the air conditioner and air conditioner compressor all the time once a desired vehicle cabin temperature is reached.
Vehicle cabin temperature can be controlled for high capacity air conditioning systems via mechanically coupling and decoupling the air conditioner to the source supplying energy to the compressor. For example, the compressor clutch can be activated when cabin temperature increases above a desired cabin temperature by a predetermined amount. Conversely, the compressor clutch can be deactivated when cabin temperature decreases below the desired cabin temperature by a predetermined amount. However, mechanically coupling and decoupling the air conditioner compressor to the energy source can be noticeable and objectionable to the driver of the vehicle.
The inventors herein have recognized the above-mentioned disadvantages and have developed method for controlling an air conditioner compressor of a vehicle, comprising: reducing a refrigerant pressurization capacity of the air conditioning compressor before engaging and disengaging the air conditioner compressor to an energy conversion device that supplies rotational energy to the air conditioner compressor.
By adjusting an air conditioner compressor displacement command before engaging and disengaging the air conditioner from an energy supply, it may be possible to reduce torque disturbances of the vehicle driveline. For example, when a length of stroke of an air conditioner compressor piston is reduced, an amount of torque to turn the compressor may be reduced. Consequently, changes in output torque of the energy source may be less noticeable to the vehicle driver when the air conditioner compressor is coupled to an energy source while less torque is necessary to turn the air conditioner compressor. Similarly, changes to the output torque of the energy source may be less noticeable to the driver when the air conditioner compressor is uncoupled from the energy source while less torque is necessary to turn the air conditioner compressor.
The present description may provide several advantages. Specifically, the approach may improve transitions between loading and unloading an air conditioner compressor to a vehicle powertrain. In addition, the approach may improve fuel control when the air conditioner compressor is coupled to an engine since changes in engine load may be reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.